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In this case, after receipt of the proceed-to-select signal GA. the subscriber keys a three-digit number indicating that the connection is to be established by an operator in the outgoing international exchange {ARM). After receipt of the numerical information by the register in the transit centre, which at the same time is international centre, a wait signal, INTLX MOM, must be sent to the A subscriber to indicate that the call has been received and queued. The backward channel must change to stop polarity immediately before this wait signal. As the connection will be charged by an operator, no tariff has been sent to the terminal exchange and consequently no tariff pulses will be sent to the subscriber's meter. From the charging point of view, therefore, the change to stop polarity is of no significance. When the call, after being queued, arrives at the operator, the exchange identity signal and the number of the operator's position, e.g. INTLX MADRID 01, are transmitted, after which the A subscriber's answer-back is automatically tripped for identification of the latter. The operator then connect an international register to the circuit, whereby a second proceed-to-select signal GA is sent to the A subscriber, who sends Fig. 13 Signalling on the chain of circuits A subscriber — terminal exchange ARB-transists centre ARM international centre in an other country employing Type A signalling for a fully automatic international call from the A subscriber TxA A-subscriber's teleprinter and control unit A Subscriber's line, single current B Junction circuit between ARB and ARM C International circuit T A-subscriber's tariff zone K A-subscriber's class 1 Proceed-to-select signal 2 Destination code 3 Identity signal from international transit centre ARM and answer-back trip signal 4 A-subscriber's answer-back with his number 5 Proceed-to-select signal 6 B subscriber's national number followed bu cnd-of-sele^tion — or - 7 B subscriber's answer-back 8 B subscriber's national number followed by end-of-selection + 16
the entire international number, destination code and national number proceded by figures shift and the digit zero, the latter in order to indicate an international call. The signalling diagram thereafter shows the signalling in the case that the destination country has Type B signalling with dial selection and non-automatic tripping of the B subscriber's answer-back. After receipt of the callconnected signal the international register in the outgoing exchange sends, in this case, an answer-back trip signal to the B subscriber. The A subscriber thus receives the same call-connected signal, i.e. the B subscriber's answerback, on both national and international calls. Signalling for Outgoing Fully Automatic International Traffic The signalling diagram in fig. 13 shows signalling on the chain of circuits TxA—ARB-ARM—international centre in another country with Type A signalling for fully automatic international traffic. The diagram is based on the assumption of several international exchanges for outgoing traffic in the same country and that all the international routes do not exist in all international exchanges. After receipt of a proceed-to-select signal GA, therefore, the A subscriber must send the destination code for the called country. The destination code is preceded by figures shift and the digit zero. The diagram is also based on central charging in the international centre by means of toll-ticketing equipment (the principle of charging on subscriber's meters for part of the international traffic may, however, also be used in the system). Charging by toll-ticketing means that the backward channel to the terminal exchange, as in the semi-automatic case, can be reversed to stop polarity for signalling, in this case, of identity signal INTLX followed by an answer-back trip signal. The toll-ticketing equipment receives the answer-back for identification of the A subscriber, whose answer-back should therefore include the subscriber's number. The second proceed-to-select signal GA is sent to the A subscriber, who then sends the B subscriber's number followed by either + (Combination 26) or - (Combination 1). If the latter <strong>com</strong>bination is sent, the punched card is immediately set aside after clearing of the connection and the subscriber, after a renewed call to a service position, can be informed of the charge for the international connection. Summary As will be evident from this account L M Ericsson telex system contains equipments of such flexibility that within the framework of CCITT's re<strong>com</strong>mendations, the exchanges can interwork with any other system. This applies equally on the national and international planes. On the national plane ARB and ARM exchanges are interworking with other systems in Canada. Norway, Spain and Yugoslavia. Internationally a number of countries with different signalling systems are interworking with the intercontinental ARM exchanges in Montreal, Vancouver and Sydney, all three of which are connected to the Round-the-World Commonwealth Cable Scheme. 17
Page 1: 1 1968
Page 4 and 5: Stored Program Controlled Telephone
Page 6 and 7: Signalling in L M Ericsson Telex Sy
Page 8 and 9: On physical subscriber lines other
Page 10 and 11: In a new Recommendation U 11, CCITT
Page 12 and 13: Automatic Tripping of B Subscriber'
Page 14 and 15: egister in ARM selects a new circui
Page 16 and 17: show the signalling both for single
Page 18 and 19: Fig. 11 gnalling for setting up a c
Page 22 and 23: Similar intervvorking exists with t
Page 24 and 25: The capital cost of the telex syste
Page 26 and 27: Fig. 1 Traffic distribution by dist
Page 28 and 29: Fig-3 Charging principles Zone char
Page 30 and 31: Transmission Considerations The obj
Page 32 and 33: A variety of special subscriber mar
Page 34 and 35: to be tripped. The calling subscrib
Page 36 and 37: References 1. C.C.T.T. Illrd Plenar
Page 38 and 39: Corrugating Machine The aim in the
Page 40 and 41: Laying The corrugated duct may have
Page 42 and 43: New Factory Opened at Ostersund L M
Page 44 and 45: Dirivox and Centrum in the Soviet U
Page 46: The Ericsson Group Associated and c

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